The stretching term in the vorticity transport equation is found to be the main mechanism to reduce the degree of mixing in axisymmetric plume.

Long-term exercises should include peroneal strengthening in both dorsiflexion and plantar flexion, as well as continued Achilles tendon stretching.

If the pressure is large or long-term bent back, in fact, the "hump-back" through stretching exercises to correct, relieve muscle stiffness, chest extended, open-minded, would feel better Oh!